Cofferdam



D. LIVINGSTONE COFFERDAM Oct. 19, 1937.

Filed July 25, 1936 2 Sheets-Sheet 1 ETTDY':

Oct.V `19, 1937. D. LIVINGSTONE Filed July 25, 1936 2 Sheets-Sheet 2 www M Patented oct. 19, 1937 UNITED STATES PATENT OFFICE COFFERDAM Daniel Livingstone, Nantasket, Mass.

Application July 25, 1936, Serial No. 92,579

' 1- Claim.

My invention relates to a coierdam structure for use in excavating holes for poles, posts and the like and it has for its object to provide an lefficient and inexpensiveV portable coiferdam 5 structureA through the use of which the operation n of planting or erecting poles, posts and the like is facilitated, particularly in situations wherev there is quicksand or where the ground is loose or sandy. y y

To these ends I have provided a portable cofferdam unit having the peculiar features of construction and'mode of use set forth in the following description, the several novel features of the invention being separately pointed out and defined in the claim at' the close thereof.

In the accompanying drawings:-

Figure 1 is a side elevation of a coiferdam structure constructed in accordance with this invention.

Figure 2 lis an elevation of another side of the structure shown in Fig. 1.

Figure 3 is a section on line 3-3 of Fig. 1.

Figure 4 illustrates the manner in which my new cofferdam structure is used.

` The illustrated embodiment of my invention is an elongate tubular metallic unit which may measure, for example,eighteen inches in diameter and three feet in length when designed for use in connection with the erection of poles for 30 supporting electric light and power conductors.

As herein shown this unit consists of two imperforate semicylindrical metallic sections I each of which is interiorly and exteriorly smooth and longitudinally level throughout except that a small bead or flange may beprovided upon the outside and at the top thereof, as shown. 'I'hese sections are separably fastened together at their opposite sides to form an imperforate tubular cofferdam unit or Vmember by two removable pintles II which extend loosely through intermeshed apertured' lugs I2 provided at opposite sides of the sections.

Each .semicylindrical section l0 is provided at its rupper end-midway between its opposite sideswith an aperturedlug I3, while its lower end is cut away or rounded as at I4 so that when the two sections are secured together by the pintles II the lower end of the tubular structure y thus formed isprovided with two oppositely disposed indentures I5 as will be clear from Figs. Zand 4.

The above described cofferdam structure is for use in digging holes for poles, posts and the like,

in locations where the land is boggy, sandy or 55 loose,'or where there is quicksand. In making a hole the latter is started and the cofferdam inserted therein after which the excavating is continued within the coiferdam and as the earth is removed the coiferdam follows, or is caused to follow, the bottom of the hole downwardly, the more or less pointed lower ends of the sections I0 permitting the latter to be forced downwardly into quicksand or soft ground as the material at the lower end of the cofferdam is removed from the latter. During the progress of the work the indentures I 5 also give access to the earth alongside of the lower end of the coierdam.

When the hole is of the desired depth the pole I 6 is placed within the coierdam as shown in Fig. 4, with a suitable tackle, not shown, attached to its upper portion. The rope of this tackle is then threaded through and tied or otherwise fastened to one or both of the eyes I3 after which the tackle is operated to pull the cofferdam upwardly out of the hole.

When the coierdam is above the ground one 1 of the pintles I I is removed thus freeing the two sections ID so that they can be swung away from each other on the remaining pintle as a pivot or hinge, thus opening the cofferdam so that it can be removed from the pole for use at another location.

Each pintle I I is made at its upper end with a head IIa in the form of an eye for engagement with a hook or other tool by means of which it is conveniently removed as described.

What I claim is:

A portable cofferdam structure comprising a pair of metallic sections each made with an imperforate semicylindrical body portion provided along its opposite sides with a row of longitudinally apertured lugs alternating and intermeshing with the lugs of the other section so as t0 provide an elongate and imperforate cylindrical tubular member whose interior and exterior surfaces are longitudinally smooth and level from a point closely adjacent to their upper ends to their lower extremities, said sections being pointedly tapered at their lower ends and each made at its upper end with an upstanding apertured lug for engagement with the rope of an overhead hoisting tackle, and a pair of pintles, one removably mounted within the intermeshing apertured lugs at one side of said member and the other removably mounted within the intermeshing apertured lugs at the opposite side of said member, each f of said pintles being made at its upper end with an eye disposed above the upper end of said member by means of which said pintle is removed to disconnect said sections.

DANIEL LIVINGSTONE. 

